Authors:M.A.A. Wijayawardena; M. Megharaj; R. NaiduPages: 175 - 234Abstract: Publication date: 2016 Source:Advances in Agronomy, Volume 138 Author(s): M.A.A. Wijayawardena, M. Megharaj, R. Naidu Exposure to chemical mixtures is a common and important determinant of toxicity in human and environmental health issues. Although there is a wealth of information on single metal interactions, very few studies have been conducted on the effects of mixtures of heavy metals on environmental quality and human health. Current national regulatory guidelines for soils are based solely on individual metal and metalloids concentrations. However, heavy metals and metalloids do not exist in isolation at the majority of sites. Soil properties such as pH, Eh, clay minerals, and cation exchange capacity influence multiple metal interactions. There are numerous adverse health effects on human, animals, and the environment due to mixed metal exposure resulting from additive and synergistic interactions even when concentrations of the individual metals are below their ecotoxicological benchmark levels. Two key strategies currently recognized as suitable for predicting toxicity of a mixture are: first, concentration addition, also known as Loewe additivity and second, effect addition, also referred to as the Bliss model of independent action. In this review we draw attention to research illustrating the interactions of multiple metal contaminants and their potential health impacts.

Authors:M.L. Jat; J.C. Dagar; T.B. Sapkota; Yadvinder-Singh; B. Govaerts; S.L. Ridaura; Y.S. Saharawat; R.K. Sharma; J.P. Tetarwal; R.K. Jat; H. Hobbs; C. StirlingPages: 127 - 235Abstract: Publication date: 2016 Source:Advances in Agronomy, Volume 137 Author(s): M.L. Jat, J.C. Dagar, T.B. Sapkota, Yadvinder-Singh, B. Govaerts, S.L. Ridaura, Y.S. Saharawat, R.K. Sharma, J.P. Tetarwal, R.K. Jat, H. Hobbs, C. Stirling During the past two centuries, the world has witnessed a remarkable increase in the atmospheric concentrations of the greenhouse gases (GHGs), namely carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), as a result of human activities after 1750 (preindustrial era). During 1750 the concentrations for these gases were 280ppm, 715 ppb, and 270 ppb, respectively which increased to 379ppm, 1774 ppb, and 319 ppb, respectively in 2005. It showed an increase of 0.23, 0.96, and 0.12% annually. The same has further increased to 385ppm, 1797 ppb, and 322 ppb, respectively in 2008 representing 1.6, 1.2, and 0.9% increase, respectively from 2005 levels at an annual increase of 0.53, 0.43, and 0.31%, annually. Increase in atmospheric CO2 promotes growth and productivity of plants with C3 photosynthetic pathway but the increase in temperature, on the other hand, can reduce crop duration, increase crop respiration rates, affect the survival and distribution of pest populations, and may hasten nutrient mineralization in soils, decrease fertilizer-use efficiency, and increase evapotranspiration. The water resources which are already scarce may come under enhanced stress. Thus, the impact of climate change is likely to have a significant influence on agriculture and eventually on the food security and livelihoods of large sections of the urban and rural populations globally. The developing countries, particularly in South Asia and Latin America, with diverse agroclimatic regions, challenging geographies, growing economies, diverse agricultural production systems, and farm typologies are more vulnerable to the effect of climate change due to heavy dependence on agriculture for livelihood. These regions also are demonstrating poor coping mechanisms to adapt to these challenges, and as a result there is evidence of negative impacts on productivity of wheat, rice, and other crops to varying extent depending on agroecologies. Upscaling of modern technologies such as conservation and climate smart agriculture, judicious utilization of available water for agriculture through microirrigation and water saving technologies, developing multiple stress-tolerant crop cultivars and biotypes through biotechnological tools, restoration of degraded soils and waters, promoting carbon sequestration through alternate production technologies and land use, and conservation of biodiversity must be promoted at regional and country level to ensure durable food and nutritional security. Reliable early warning system of environmental changes, their spatial and temporal magnitude, coupled with policies to support the diffusion of this information, can help interpret these forecasts in terms of their agronomic and economic implications for the benefit of farmers and to provide agriculture-dependent industries and policymakers with more informed options to support farmers. These countries need to formulate both short-term and long-term policies for improvement, sustenance, and protection of natural resources. There is an urgent need for capacity building through international collaboration in order to develop databases and analysis systems for efficient weather forecasting as well as preparing contingency plans for vulnerable areas. The objectives of this paper are to summarize the available information on adaptation strategies and the mitigation options for climate change to meet the food security in South Asia and Latin America.

Authors:B. Colon; G.S. ToorAbstract: Publication date: Available online 7 September 2016 Source:Advances in Agronomy Author(s): B. Colon, G.S. Toor Concerns and knowledge of pharmaceuticals and personal care products (PPCPs) presence in agricultural soils have led to research efforts to assess the uptake and translocation of PPCPs into edible parts of crops. This interest stems because PPCPs can be transferred from soils to food crops due to the use of treated wastewater, also called reclaimed or recycled water, for irrigation. We identified and reviewed 28 plant uptake studies relevant to food crops irrigated with reclaimed water to better understand how PPCPs are taken and translocated in food crops. The food crops included bulb vegetables, cole crops, cucurbits, cereal grains, fruiting and leafy vegetables, herbs and spices, and roots and tuber vegetables. Of the 28 studies of reclaimed water use, 22 were conducted in controlled or greenhouse settings and 6 were field studies. The data from these studies collectively showed that PPCPs can be taken up and then translocate into edible parts of food crops at detectable levels. However, human exposure of PPCPs from food crops is expected to be low due to the smaller concentrations found in food crops. Our major knowledge gap in current understanding of PPCPs uptake by crops irrigated with reclaimed water are lack of sufficient field data as only a limited number of field studies have been conducted. As reclaimed water use is anticipated to increase to meet agriculture water demands, we suggest that additional field studies are needed to better understand the uptake and translocation of PPCPs by crops over multiple growing seasons in different parts of the world.

Authors:J.W. Stuckey; D.L. Sparks; S. FendorfAbstract: Publication date: Available online 7 September 2016 Source:Advances in Agronomy Author(s): J.W. Stuckey, D.L. Sparks, S. Fendorf Arsenic (As), a toxic metalloid common throughout the Earth's crust, accounts for the most widespread poisoning of a human population in history. Within the major deltas of South and Southeast (S/SE) Asia, rivers annually deposit As-bearing iron oxides, oxyhydroxides, and hydroxides (collectively referred to as Fe oxides hereafter) derived from the Himalaya. The high primary productivity and monsoonal flooding in the tropical deltas promote microbially driven As release to groundwater through dissimilatory As(V)/Fe(III) reduction. Groundwater is a primary source of drinking and irrigation water in the region, especially within rural areas. Prolonged consumption of As-contaminated groundwater can lead to a multitude of serious health complications, including cancer and cardiovascular disease. Here we define the parameters controlling the locations of active microbially driven As release to groundwater, including suboxic/anoxic conditions, microbial communities capable of mediating As(V)/Fe(III) reduction, the reactivity of As-bearing Fe oxides, and the sources and reactivity of organic carbon (C). Conditions for microbially driven As release are optimized where the reactivity of both As-bearing Fe oxides and organic C is greatest. Optimal conditions for As release are found in near-surface sediments of the Red River, under permanent wetlands of the Mekong River, and at depth (∼20m) in the Yangtze River Basin, whereas findings are variable within the Bengal Basin. Land and water management changes resulting in increased flood duration in deltaic environments may result in new locations of active microbial As release to groundwater.

Authors:Ch. Srinivasa Rao; K.A. Gopinath; J.V.N.S. Prasad; Prasannakumar; A.K. SinghAbstract: Publication date: Available online 28 August 2016 Source:Advances in Agronomy Author(s): Ch. Srinivasa Rao, K.A. Gopinath, J.V.N.S. Prasad, Prasannakumar, A.K. Singh The world population is expected to increase by a further three billion by 2050 and 90% of the three billion will be from developing countries that rely on existing land, water, and ecology for food and well-being of human kind. The Intergovernmental Panel on Climate Change (IPCC) in its fifth assessment report (AR5) stated that warming of the climate system is unequivocal and is more pronounced since the 1950s. The atmosphere and oceans have warmed, the amounts of snow and ice have diminished, and sea level has risen. Each of the last three decades has been successively warmer at the earth's surface than any preceding decade since 1850 and the globally averaged combined land and ocean surface temperature data as calculated by a linear trend show a warming of 0.85°C (0.65–1.06°C) over the period of 1880–2012. World Meteorological Organization (WMO) ranked 2015 as the hottest year on record. Climate change poses many challenges to growth and development in South Asia. The Indian agriculture production system faces the daunting task of feeding 17.5% of the global population with only 2.4% of land and 4% of water resources at its disposal. India is more vulnerable to climate change in view of the dependence of huge population on agriculture, excessive pressure on natural resources, and relatively weak coping mechanisms. The warming trend in India over the past 100 years has indicated an increase of 0.6°C, which is likely to impact many crops, negatively impacting food and livelihood security of millions of farmers. There are already evidences of negative impacts on yield of wheat and paddy in some parts of India due to increased temperature, water stress, and reduction in number of rainy days. Significant negative impacts have been projected under medium-term (2020–39) climate change scenario, for example, yield reduction by 4.5–9%, depending on the magnitude and distribution of warming. Since agriculture currently contributes about 15% of India's gross domestic product (GDP), a negative impact on production implies cost of climate change to roughly range from 0.7% to 1.35% of GDP per year. Indian agriculture, with 80% of farmers being smallholders (<0.5ha) having diverse socioeconomic backgrounds, is monsoon-dependent rainfed agriculture (58%), about 30% of population undernourished, migration from rural to urban regions, child malnutrition etc., has become more vulnerable with changed climate or variability situations. During the past decade, frequency of droughts, cyclone, and hailstorms increased, with 2002, 2004, 2009, 2012, and 2014 being severe droughts. Frequent cyclones and severe hailstorms in drought prone areas have become common. Eastern part of the country is affected by seawater intrusion. Reduced food grain productivity, loss to vegetable and fruit crops, fodder scarcity, shortage of drinking water to animals during summer, forced migration of animals, severe loss to poultry and fishery sectors were registered, threatening the livelihoods of rural poor. Enhancing agricultural productivity, therefore, is critical for ensuring food and nutritional security for all, particularly the resource-poor, small, and marginal farmers who would be the most affected. In the absence of planned adaptation, the consequences of long-term climate change on the livelihood security of the poor could be severe. In India, the estimated countrywide agricultural loss in 2030 is expected to be over $7 billion that will severely affect the income of at least 10% of the population. However, this could be reduced by 80%, if cost-effective climate resilient measures are implemented. Climate risks are best addressed through increasing adaptive capacity and building resilience which can bring immediate benefits and can also reduce the adverse impacts of climate change. Climate resilient agriculture (CRA) encompasses the incorporation of adaptation and resilient practices in agriculture which increases the capacity of the system to respond to various climate-related disturbances by resisting damage and ensures quick recovery. Such disturbances include events such as drought, flood, heat/cold wave, erratic rainfall pattern, pest outbreaks, and other threats caused by changing climate. Resilience is the ability of the system to bounce back and essentially involves judicious and improved management of natural resources, land, water, soil, and genetic resources through adoption of best bet practices. CRA is a way to achieve short- and long-term agricultural development priorities in the face of climate change and serves as a bridge to other development priorities. It seeks to support countries and other actors in securing the necessary policy, technical and financial conditions to enable them to: (1) sustainably increase agricultural productivity and incomes in order to meet national food security and development goals, (2) build resilience and the capacity of agricultural and food systems to adapt to climate change, and (3) seek opportunities to mitigate emissions of greenhouse gases (GHGs) and increase carbon sequestration. These three conditions (food security, adaptation, and mitigation) are referred to as the “triple win” of overall CRA.PubDate: 2016-08-30T00:55:03ZDOI: 10.1016/bs.agron.2016.06.003

Authors:Q.-L. Fu; C. Liu; V. Achal; Y.-J. Wang; D.-M. ZhouAbstract: Publication date: Available online 19 July 2016 Source:Advances in Agronomy Author(s): Q.-L. Fu, C. Liu, V. Achal, Y.-J. Wang, D.-M. Zhou Due to the extensive application of aromatic arsenical additives (AAAs) in the animal feeding industry worldwide, soil contamination by AAAs has attracted great interests recently. This paper comprehensively reviewed the recent advances in the detection, environmental behaviors, toxicities, and remediation for AAAs in soil system. As of now, HPLC-ICP-MS and HPLC-ESI-MS/MS are the most predominent techniques used to separate and determine the species and concentrations of AAAs as well as their metabolites. Sorption and biotic transformation are the two main processes in affecting the fate of AAAs in soil, but few works have focused on their aerobic degradation, plant accumulation, and transformation mechanisms. Arsenic is highly toxic, and the toxicity of arsenic species ranked in the order of MMA(III) (monomethylarsonic acid)>iAs(III)>iAs(V)>organic As. However, the combined toxicity of different arsenic species to soil organisms and their potential human risk should be emphasized in the future. It has been found that Fe- and/or Al-containing drinking-water treatment residuals are promising materials to immobilize arsenic in AAAs polluted sites, but to reduce AAAs application in animal feeding industry will be vital for soil environmental protection.

Authors:U.K. Behera; FranceAbstract: Publication date: 2016 Source:Advances in Agronomy, Volume 138 Author(s): U.K. Behera, J. France Agriculture in India and other Asian countries is facing multiple and complex challenges which are expected to become more severe with the passage of time. Some of the major challenges are sustainability of natural resources, impact of climate change and decline in factor of productivity. Besides, the declining trend in size of land holding poses a serious challenge to the profitability and sustainability of farming. In view of the decline in per capita availability of land, it is imperative to develop strategies and agricultural technologies that enable adequate employment and income generation, especially for small-holders (farmers with <2.0ha of land) who constitute the vast majority of the farming community in the developing world. No single farm enterprise, such as a typical mono-cropping system, is likely to be able to sustain the small-holder farmer. Integrated farming systems (IFS) are less risky if managed efficiently, as they benefit from synergisms among enterprises, diversity in produce, and environmental soundness. On this basis, IFS have been suggested for the development of small and marginal farms across Asia, and researchers have developed strategies which have benefited small-holder farmers by providing additional income and employment and minimizing risk. However, these IFS have not been promulgated and promoted effectively. The present review helps to remedy this by providing comprehensive information on the concepts and advantages of IFS for small-holder farmers, which is lacking at present. The review covers the key literature on farming systems and allied aspects published over the period 1970–2015.

Authors:Ashish Kumar; Srivastava Ratnakumar Pasala Paramjit Singh Minhas Penna SuprasannaAbstract: Publication date: Available online 2 February 2016 Source:Advances in Agronomy Author(s): Ashish Kumar Srivastava, Ratnakumar Pasala, Paramjit Singh Minhas, Penna Suprasanna Increasing agricultural productivity and sustainability will have to be prioritized to enhance food production. The major challenge toward this emanates from multiple stress factors and unpredictable climatic conditions. Thus, it is critical to understand and characterize the plant responses to changing environmental conditions. Needless to say, plant breeding has contributed a great deal to crop improvement over the past decades and is still supplementing the biotechnological advancement to bring technologies for enhancing crop yield. In recent years, although several stress tolerant transgenic lines have been developed; however, their performance in farmer's field is still to be tested. In this regard, present review describes Low External Input and Sustainable Agriculture (LEISA) based agriculture wherein low concentration of plant bioregulators (PBRs) are applied externally at a suitable developmental stage to boost the plant signaling which finally leads to enhanced growth and crop yield. There is a wide range of chemical- and hormone-based PBRs used for different crops and here in, we have proposed a unified mechanism for their mode of action. This is based upon PBRs ability to fine tune plant redox homeostasis which regulate root growth for improving plant water/nutrient status, photosynthetic efficiency and source–sink homeostasis for enhanced crop yield and metabolism for overall improvement in plant growth. The knowledge gaps and quality control aspect have also been discussed to ensure the adoptability and applicability of PBRs on a wider scale.

Authors:A.S. Lopes; L.R. Guimarães GuilhermePages: 1 - 72Abstract: Publication date: Available online 19 March 2016 Source:Advances in Agronomy Author(s): A.S. Lopes, L.R. Guimarães Guilherme The rise of agriculture production in the Brazilian savanna is seen as one of the greatest achievements of worldwide agricultural science in the 20th century. Yet, reaching this current situation was, and still is, not an easy task. Actually, until the 1960s, 23% of Brazil (2million km2) was occupied by a savanna-like vegetation generally called “Cerrado,” developed in highly weathered soils, with particularly low natural fertility, used for extensive beef cattle production on unimproved pastures. This review paper intends to summarize a pioneer survey study by Dr Alfredo Lopes on “Cerrado” soils in the mid-1970s aiming to: (1) revisit the main chemical and physical properties of 518 topsoil samples under “Cerrado” vegetation in Central Brazil; (2) compare these results with some of the critical levels suggested for soil fertility interpretation; and, (3) study some relations among soil physical, chemical, and mineralogical characteristics in selected 44 topsoil samples with data concerning available water, phosphorus fixation, charge attributes, as well as extractable and total zinc. Besides stressing on the importance of adequate management strategies to allow the incorporation of these low natural fertility soils into successful crop production, we also highlight the historical importance of international collaborations that contribute to the development of soil fertility evaluation and agronomic–economic research programs on tropical soils in the Brazilian Cerrados. Lastly, additional comments are provided concerning the need of strategic actions and appropriate political decisions for the continuous sustainable development of this region.

Authors:G. Mi; F. Chen; L. Yuan; F. ZhangPages: 73 - 97Abstract: Publication date: Available online 11 June 2016 Source:Advances in Agronomy Author(s): G. Mi, F. Chen, L. Yuan, F. Zhang The importance of root system in supporting shoot growth has been extensively studied and discussed under nutrient and/or water deficit conditions, but much less in the context of intensive cropping system in which plant density is high and nutrients can be supplemented through fertilizer application to match the requirement of plant growth and grain yield formation. Taking maize as a model crop, the ideotype root system architecture (RSA) under intensive production conditions was discussed in regard to high yield and resource use efficiency. An ideotype maize RSA should meet the requirements not only for efficient use of water and unevenly distributed nutrients, but also for greater root-lodging resistance. In addition, the construction of RSA should adapt to efficient utilization of carbon and/or nutrients within the plant. The embryonic root system and the postembryonic root system should be considered separately because they are controlled by different genetic mechanisms and function in different growth stages during which soil environment varies. Considering all the previously mentioned factors, we proposed two separate models for the ideotype maize RSAs at seedling stage and at adult plant stage, and the characteristics of axile root and lateral root traits for each model are described in detail.

Authors:A.E. HarteminkPages: 73 - 126Abstract: Publication date: Available online 8 February 2016 Source:Advances in Agronomy Author(s): Alfred E. Hartemink The soil is defined differently by soil scientists, and its definition has changed over time. This paper reviews how the definition of the soil has changed since the early 1800s by selecting and listing 81 definitions given in a wide range of soil science books, handbooks, glossaries, and dictionaries. Initial definitions of the soil were based on developments in agricultural chemistry or geology. The soil was seen as a production factor (medium) for agriculture that needed to be understood before it could be improved, or the soil was defined as disintegrated rocks mixed with organic matter. Definitions were rudimentary reflecting the overall level of understanding. Soil variation was not well understood. Overarching soil definitions appeared in the late 1800s following some major shifts in the understanding and knowledge about soils. The definition of the soil was particularly relevant for soil survey and in soil classification because it affected how soils were viewed in the field and represented in a two dimensional way (soil maps). Both the World Reference Base (WRB) and Soil Taxonomy have defined the soil, but standard field books describing soils often lack a definition. Most of the definitions in dictionaries and glossaries are detailed stressing the organic and inorganic part of the soil as well the origin, complexity, and some of its functions. Current soil definitions have a more environmental outlook reflecting the broadening of the soil science discipline but definitions will change following scientific advances and discovery. Soils are defined differently by subdisciplines. Considerable research is conducted nowadays outside soil science departments and research centres, and for some researchers the soil may solely be a medium—just as it was in the mid-1800s. The effect of increased specialisation and expansion in soil science causes the detail of the investigation to prevail over the idea of soil as a complex dynamic system that is part of a much wider Earth system. This review ends with a proposal for a scientific definition of soil, and a definition for lay persons and the general public.

Authors:H. Wijesekara; N.S. Bolan; M. Vithanage; Y. Xu; S. Mandal; S.L. Brown; G.M. Hettiarachchi; G.M. Pierzynski; L. Huang; Y.S. Ok; M.B. Kirkham; C.P. Saint; A. SurapaneniPages: 97 - 173Abstract: Publication date: Available online 5 April 2016 Source:Advances in Agronomy Author(s): H. Wijesekara, N.S. Bolan, M. Vithanage, Y. Xu, S. Mandal, S.L. Brown, G.M. Hettiarachchi, G.M. Pierzynski, L. Huang, Y.S. Ok, M.B. Kirkham, C. Saint, A. Surapaneni Globally, around 0.4×106 km2 area of land is estimated to be disturbed by mining activities, thereby contributing to severe environmental consequences including the generation of large amounts of mine spoils. The shortfall in topsoil due to poor striping practices and low levels of organic matter have been identified as common problems in rehabilitation of mining spoil. High heavy metal concentrations in mine spoil can adversely impact microbial activity and subsequent revegetation succession. The release of acids associated with mine spoils (ie, acid mine drainage through oxidation of pyrite) can also create adverse effects on the surrounding vegetation. Large quantities of biowaste, such as manure compost, biosolids, and municipal solid waste (MSW) that are low in contaminants [including metal(loid)s] can be used to rehabilitate mine spoils. These biowastes provide a source of nutrients and improve the fertility of spoils. These biowastes also act as a sink for metal(loid)s in mine tailings reducing their bioavailability through adsorption, complexation, reduction, and volatilization of metal(loid)s. This review provides an overview of the sources of biowastes and the current regulations for utilization; describes their benefits in terms of improving the physical, chemical, and biological properties of mine spoils; and elaborates on the role of the utilization of biowastes on mine spoil rehabilitation through several case studies. Finally, future research needs and strategies are identified in terms of sustainable biowaste utilization in mine spoil rehabilitation.

Authors:K. Lorenz; R. LalPages: 99 - 152Abstract: Publication date: Available online 11 June 2016 Source:Advances in Agronomy Author(s): K. Lorenz, R. Lal Organic agriculture (OA) is practiced on 1% of the global agricultural land area and its importance continues to grow. Specifically, OA is perceived by many as having less negative effects on the environment than conventional agriculture because applications of soluble mineral fertilizers, and synthetic herbicides and pesticides are prohibited. However, scientific evidence for better environmental impact is scanty. Specifically, yields under OA are about 19% lower and the attendant lower soil carbon (C) inputs together with tillage for weed control contributes to lower profile soil organic carbon (SOC) stocks under OA. Less well known are the effects on soil inorganic carbon (SIC) stocks. Otherwise, soils managed by OA may emit less carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). Specifically, by the adoption of OA practices 1.65Mg CO2 ha−1 y−1 may be sequestered in the top 20-cm layer. Further, N2O emissions from soils managed by OA may be 492kg CO2 eq. ha−1 y−1 lower than those from conventionally managed soils. Under OA management, a higher CH4 uptake of 3.2kg CO2 eq. ha−1 y−1 may be observed for arable soils. The soil, air, and water quality may also be enhanced by OA whereas effects on biodiversity are mixed. Thus, there is an urgent need to strengthen the database on environmental impacts of OA by establishing and studying long-term field experiments in all major biomes and principal soils. Consumer demand for organic products will continue to grow driven by food safety concerns and increasing affluence. Due to lower yields, however, natural ecosystems may be increasingly converted to agroecosystems to meet the demand with less well-known consequences for the environment. Nonetheless, scientific interest in OA is less than a century old, and there is significant potential to lessen its environmental impacts while methods derived from OA can contribute to sustainable intensification of agricultural systems.

Authors:P. Filippi; B. Minasny; S.R. Cattle; T.F.A. BishopPages: 153 - 214Abstract: Publication date: Available online 22 July 2016 Source:Advances in Agronomy Author(s): P. Filippi, B. Minasny, S.R. Cattle, T.F.A. Bishop Soils naturally change through time, but anthropogenic activity has significantly altered the rate and direction of soil change. As well as further impacts of human activity on soil into the future, it is also expected that recent climatic shifts will have an important effect. There are a variety of methods of monitoring changes in soil, but a shift in focusing on change over larger areas has increased the implementation of national and regional soil monitoring networks. Despite the advantages of these networks, their time and resource consuming nature is often a constraint, which has led to the utilization of “legacy data” to detect spatiotemporal changes in soil. Although using legacy data has its challenges, it is invaluable in detecting historical shifts in soil condition. Additionally, it is also imperative to predict how climate and land use will influence how soil changes in the future through the use of temporal soil models. There have been many recent increases in the number and quality of these models, and as we strive to move away from laborious and expensive soil surveys, these models become more invaluable. This review reinforces the cruciality of soil monitoring, and suggests that we should focus on the wealth of soil legacy data available. We should place more attention on monitoring several important soil properties at various vertical depths, attempt to better understand the impact that climatic shifts will have on soil, and take full advantage of available statistical analytical methods to detect soil change. With all this in place, the accurate representation of past and future changes in soil condition is possible, providing a guide for future land use adaptation.

Authors:D. Montalvo; F. Degryse; R.C. da Silva; R. Baird; M.J. McLaughlinPages: 215 - 267Abstract: Publication date: Available online 11 June 2016 Source:Advances in Agronomy Author(s): D. Montalvo, F. Degryse, R.C. da Silva, R. Baird, M.J. McLaughlin Zinc (Zn) is an essential micronutrient for plants and humans. Millions of hectares of agricultural land are affected by Zn deficiency and it has been estimated that about one-third of the world's population is Zn deficient. One of the strategies that has been successfully used to tackle Zn deficiency is the application of Zn fertilizers. A large array of Zn sources is available in the market, although the most commonly used fertilizers are ZnO and ZnSO4. The availability of Zn fertilizers is affected by the chemical reactions of Zn with the soil which are also affected by the chemical and physical properties of the fertilizer (eg, granule size or physical state solid vs fluid, water solubility of Zn) and the fertilizer application method. Application of fertilizers to the soil at sowing is an effective strategy to increase soil available Zn and crop yields, and the relative effectiveness of sulfate and oxide sources of Zn varies with placement. Cogranulating Zn with phosphorus fertilizers can reduce effectiveness due to formation of insoluble Zn phosphates, but various technologies are becoming available to circumvent this issue. The application of foliar Zn sprays should be considered when plants are grown in Zn-sufficient soils and the main goal is food biofortification.

Authors:H.-Y Yu; F.-B. Li; C.-S. Liu; W. Huang; T.-X. Liu; W.-M. YuPages: 279 - 317Abstract: Publication date: Available online 10 March 2016 Source:Advances in Agronomy Author(s): H.-Y Yu, F.-B. Li, C.-S. Liu, W. Huang, T.-X. Liu, W.-M. Yu Red soil is an important soil resource, which bears substantial implication for sustainable development of agriculture and healthy growth of economy. However, the red soil in China has been deteriorating in recent years and facing many threats, such as soil erosion, acidification, and pollution. Among these, contamination of heavy metals, particularly arsenic and cadmium pollution in paddy soils of the red soil regions, has become a major environmental concern. In this paper, we reviewed recent publications on iron redox cycling and its coupling to the fate of heavy metals and metalloids. The most exciting findings on the iron biogeochemistry processes include dissimilatory iron reduction, Fe(II) oxidation, and Fe2+-catalyzed recrystallization of iron (hydro)oxides, all of which contribute to the immobilization of heavy metals. Although these findings are mainly based on laboratory experiments, they provide guidance for exploring innovative remediation strategies for controlling pollution of heavy metals in paddy soils of the red soil regions. We also summarized how the iron redox cycling may be affected by other biogeochemical processes or active constituents, such as the nitrogen cycling, the sulfur cycling and humic substances. It appears that the mechanisms underlying the interactions among these multiple components and processes are not sufficiently understood and may require further studies. Finally, future research needs pertaining to iron redox cycling coupled to the fate of heavy metals are suggested. The results summarized in this review may provide insights for solving the heavy metal pollution of paddy soils in the red soil regions.